Architecture not properly configured

[jacob-carlborg]

The architecture does not seem to be properly configured. For some things, it's configured for 32bit, for some things 64bit.

dlp infer-attributes shows errors for

import std.bitmanip;

auto foo(BitArray a)
{
    return a & a;
}

With explicit --target-architecture=x86, everything works. The help text, however, shows the wrong default:

--target-architecture=x86|x86_64      Set <arch> as the target architecture [default: x86].

Originally reported here: https://github.com/jacob-carlborg/dlp/issues/8#issuecomment-758243459.